How to Package DLLs with Java Code into a Single JAR File?

Packaging JAR Files with DLL Inclusions

Question: How can you create a single JAR file that incorporates your code, a third-party JAR, and its accompanying DLL files?

Answer: To package the DLL files with your JAR, follow these steps:

1. Include the DLL files: Place the DLL files anywhere within the JAR.
2. Extract before use: Before accessing the DLLs, extract them from the JAR and store them on the hard disk.

Sample Code:

The provided Java code demonstrates a method for loading DLLs from a JAR into memory:

public class Foo {

    static {
        System.loadLibrary(ACWRAPPER);
    }

    private static void loadFromJar() {
        // Extract DLLs to a temporary location
        String path = "AC_" + new Date().getTime();
        loadLib(path, ACWRAPPER);
        loadLib(path, AAMAPI);
        loadLib(path, LIBEAU);
    }

    private static void loadLib(String path, String name) {
        name = name + ".dll";
        try {
            InputStream in = ACWrapper.class.getResourceAsStream(LIB_BIN + name);
            File fileOut = new File(System.getProperty("java.io.tmpdir") + "/" + path + LIB_BIN + name);
            OutputStream out = FileUtils.openOutputStream(fileOut);
            IOUtils.copy(in, out);
            System.load(fileOut.toString());
        } catch (Exception e) {
            throw new ACCoreException("Failed to load required DLL", e);
        }
    }
}

Notes:

• It's crucial to extract the DLLs before use, as you can't directly load them from the JAR.
• Packaging DLLs into a JAR is similar to packaging any other type of file.

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